A multi-start iterated local search with tabu list and path relinking for the two-echelon location-routing problem

The two-echelon location-routing problem (LRP-2E) is raised by the design of transportation networks with two types of trips: first-level trips serving from one main depot a set of satellite depots, to be located, and second-level trips supplying customers from these satellites. In the proposed multi-start iterated local search (MS-ILS), three greedy randomized heuristics are used cyclically to get initial solutions. Each ILS run alternates between two search spaces: LRP-2E solutions, and travelling salesman (TSP) tours covering the main depot and the customers. The number of iterations allotted to a run is reduced whenever a known solution (stored in a tabu list) is revisited. MS-ILS can be reinforced by a path-relinking procedure (PR), used internally for intensification, as post-optimization, or both. On two sets with 24 and 30 LRP-2E instances, MS-ILS outperforms on average two GRASP algorithms and adding PR brings a further improvement. Our metaheuristic also surpasses a tabu search on 30 instances for a more general problem with several main depots. It is still effective on a particular case, the capacitated location-routing problem (CLRP): In a comparison with four published metaheuristics, only one (LRGTS, Prins et al., 2007) does better.     

Effect of automatic image realignment on visuomotor coordination in simulated laparoscopic surgery

During laparoscopic surgery, the surgeon's hand-eye coordination is often disrupted by the incongruent mapping between the orientation of the endoscopic view and the actual operative field. Two experiments were conducted to examine the effect of automatic image realignment on the performance of laparoscopic surgery. The first experiment investigated how visual-motor misalignment impacted laparoscopic surgery performance. Novice subjects were randomly assigned to one of the two paired viewing conditions in a simulated laparoscopic surgery environment: 1) the endoscope was either at the center of the modeled workspace with an optical axis of 90°, or at -45° from the midline of the subjects with an optical axis 45°; 2) the endoscope was either at 0°, or at 180° from the midline of the subjects, both with an optical axis of 45°. Each group of twelve subjects performed a dynamic point-and-touch task under the assigned pair of viewing conditions, each with eight image orientations, in a repeated-measures mixed design. The second experiment examined whether the automatic realigning mechanism that was activated mid-task (such that a congruent mapping between display and control was re-established if the mapping at the beginning of the task had been misaligned) was helpful to improve performance. Twelve novice subjects performed the same task as in the first experiment in a repeated-measures design. Performance was examined under three misaligned visuomotor mappings, each followed by the realigned mapping activated by the automatic realigning mechanism. Results showed that performance was best when the endoscopic image was perfectly aligned with the actual task space (0° image orientation), but degraded progressively as a function of deviation from perfect alignment. Subjects' performance maintained a consistent pattern across 8 image orientations regardless of optical axis orientation and endoscope location. Performance was improved with the automatic realigning mechanism. It is recommended that any solution to restore the visuomotor congruency in laparoscopic surgery should first align the image with the task space. This work has implications for the design of visualization systems in laparoscopic surgery.     

Minimum variance prediction and control for adaptive optics

Adaptive Optics (AO) systems enable to compensate the adverse effects of atmospheric turbulence on ground-based telescopes’ images in real time, using a deformable mirror (DM) inserted in the telescope’s optical path, and measurements provided by a wavefront sensor (WFS). This paper revisits minimum-variance (MV) control design for astronomical AO systems in a state-space framework. It presents a survey of the modeling and control issues arising in this multi-variable disturbance rejection problem. In a linear time-invariant framework, and under some mild assumptions, the optimal solution to MV control for AO systems is shown to be a discrete-time LQG controller. This result holds for a DM with instantaneous response, and for a fairly general class of DM’s dynamics. The state-space approach is extended to Wide-field Adaptive Optics (WfAO) configurations involving several DMs and/or WFSs. Integral-action control used in existing AO systems is compared with the LQG controller. Experimental WfAO results obtained on a laboratory test bench are presented, showing significant improvement in performance. Finally, open issues and perspectives of applicative and/or theoretical interests are discussed.     

BCI Meeting 2005--workshop on signals and recording methods.

This paper describes the highlights of presentations and discussions during the Third International BCI Meeting in a workshop that evaluated potential brain-computer interface (BCI) signals and currently available recording methods. It defined the main potential user populations and their needs, addressed the relative advantages and disadvantages of noninvasive and implanted (i.e., invasive) methodologies, considered ethical issues, and focused on the challenges involved in translating BCI systems from the laboratory to widespread clinical use. The workshop stressed the critical importance of developing useful applications that establish the practical value of BCI technology.     

Adoption and Cognitive Development: A Meta-Analytic Comparison of Adopted and Nonadopted Children's IQ and School Performance.

This meta-analysis of 62 studies (N=17,767 adopted children) examined whether the cognitive development of adopted children differed from that of (a) children who remained in institutional care or in the birth family and (b) their current (environmental) nonadopted siblings or peers. Adopted children scored higher on IQ tests than their nonadopted siblings or peers who stayed behind, and their school performance was better. Adopted children did not differ from their nonadopted environmental peers or siblings in IQ, but their school performance and language abilities lagged behind, and more adopted children developed learning problems. Taken together, the meta-analyses document the positive impact of adoption on the children's cognitive development and their remarkably normal cognitive competence but delayed school performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Investigation of Functional Hemispheric Asymmetry of Language in Tinnitus Sufferers.

The authors tested functional hemispheric asymmetry through word dichotic listening and lateralized lexical decision tasks in tinnitus patients and controls stimulated by a continuous tinnitus-like noise to test the influence of a tinnitus-like external stimulation. A classic right-ear advantage was shown in the auditory task for all but right-ear tinnitus patients, who performed as equally badly when the stimuli were presented to the right and left ears. Concerning the visual task, all participants demonstrated the expected right visual field advantage for word stimuli. Moreover, those who submitted to external stimulation demonstrated normal asymmetric patterns. These data suggest a specific effect of tinnitus on central processing and provide evidence for a functional reorganization induced by this auditory phantom perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of heat-treatment environment on Ni-ferrite nanoparticle formation from coconut water precursor

The kinetics of formation of NiFe₂O₄ nanoparticles were investigated where the nanoparticles were produced by the proteic-sol–gel method using coconut water followed by annealing in (i) air, (ii) air in the presence of boron nitride (BN), or (iii) nitrogen. The sample dried at 473 K for 5.5 h was composed of small disordered NiFe₂O₄ nanoparticles in a superparamagnetic state as determined from Mössbauer spectroscopy. In general, heat treatment at high temperature leads to a nanocomposite rich in NiFe₂O₄. In air, annealing at 1173 K for 8 h favored the formation of the magnetically ordered NiFe₂O₄ inverse spinel structure, with bulk characteristics and average crystal sizes of approximately 66 nm. In a nitrogen atmosphere and in compacted BN powder under air atmosphere, the NiFe₂O₄ spinel structure stabilized for temperatures up to 873 and 773 K, respectively, however, decomposition of the NiFe₂O₄ phase into other undesired structures was observed above 873 K.     

Control and care: landlords and the governance of vulnerable tenants in houses in multiple occupation

Houses in multiple occupation (HMOs) in which tenants share facilities are housing an increasing proportion of vulnerable adults who have limited affordable housing options. However, knowledge about how these types of property are managed is limited. In this paper, we examine the governance function of HMO landlords from the perspective of landlords/landlord agents and the tenants that live within their properties. The landlord exercises control through formal and informal risk assessment of tenants and close surveillance of them. These control mechanisms may also involve direct or indirect provision of support and care to some tenants. This illustrates the complex relationship between care and control and the extent to which both are integral to the housing management of vulnerable tenants living in HMOs. We suggest that this dual function calls for a critical examination of what constitutes a ‘good landlord’.